1. Field of the Invention
The present invention relates to a golf ball, and more particularly to a golf ball made by use of a biodegradable material not harmful to the environment.
2. Prior Art
Prior-art golf balls include one-piece balls, two-piece balls, three-piece balls, and multi-layer balls having an even larger number of layers. Concrete materials used in such golf balls include, as core materials: thermoplastic elastomers such as natural rubber, butadiene rubber, isoprene rubber and styrene-butadiene rubber; and as cover materials enclosing the core: thermoplastic resins such as ionomers, polyamides, polyesters, polyetheresters, polyetheramides and thermoplastic polyurethanes, and thermoset resins such as polyureas, thermoset polyurethanes, epoxy resins, polyphenols, polysilicones and urea-melamine resins. These golf balls are mass-produced by processes such as injection molding and compression molding in a volume of some hundreds of millions of balls annually.
Used golf balls are generally disposed of in a landfill or incinerated, although a certain proportion of golf balls end up as lost balls or are otherwise abandoned to the environment. Because the above materials used as ingredients of golf balls are unlikely to be biodegradable to any substantial extent, there is some concern over the adverse impact of such abandoned golf balls on the environment. JP-A 7-213204, JP-A 2001-192023 and JP-A 2003-284800 indicate the use of biodegradable materials in the production of fishing gear, boxes for packaging golf balls, and shuttlecocks. Yet, when it comes to golf balls produced in a larger volume than these other products, there exists an unmet need for the development of technology to manufacture golf balls not harmful to the environment.